SSL/TLS Strong Encryption: How-To

This documented is intended to get you started, and get a few things
working. You are strongly encouraged to read the rest of the SSL
documentation, and arrive at a deeper understanding of the material,
before progressing to the advanced techniques.

Obviously, a server-wide SSLCipherSuite which restricts
ciphers to the strong variants, isn't the answer here. However,
mod_ssl can be reconfigured within Location
blocks, to give a per-directory solution, and can automatically force
a renegotiation of the SSL parameters to meet the new configuration.
This can be done as follows:

When you know all of your users (eg, as is often the case on a corporate
Intranet), you can require plain certificate authentication. All you
need to do is to create client certificates signed by your own CA
certificate (ca.crt) and then verify the clients against this
certificate.

# require a client certificate which has to be directly
# signed by our CA certificate in ca.crt
SSLVerifyClient require
SSLVerifyDepth 1
SSLCACertificateFile conf/ssl.crt/ca.crt

The key to doing this is checking that part of the client certificate
matches what you expect. Usually this means checking all or part of the
Distinguished Name (DN), to see if it contains some known string.
There are two ways to do this, using either mod_auth_basic or
SSLRequire.

The mod_auth_basic method is generally required when
the certificates are completely arbitrary, or when their DNs have
no common fields (usually the organisation, etc.). In this case,
you should establish a password database containing all
clients allowed, as follows:

These examples presume that clients on the Intranet have IPs in the range
192.168.1.0/24, and that the part of the Intranet website you want to allow
internet access to is /usr/local/apache2/htdocs/subarea.
This configuration should remain outside of your HTTPS virtual host, so
that it applies to both HTTPS and HTTP.

mod_ssl can log extremely verbose debugging information
to the error log, when its LogLevel is
set to the higher trace levels. On the other hand, on a very busy server,
level info may already be too much. Remember that you can
configure the LogLevel per module to
suite your needs.

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